Ah, the wise Theoden!! I have read your post many times, even printed it out to read it! You are right in so many ways. If I didn't know better, I'd swear you have been living in my house, if not my head!
It's true OW is digging her own grave. I believe she has about covered herself up.
I like your advice of stating boundaries, not punishing my H but keeping the road home smooth. That's what I've been trying to do. At times I've wondered why I was doing that. But I know I contributed to our problems so there is my reason why.
As far as what attracts him to her. I can see the madonna/whore psychological complex. I also know there was emotional attachment for him as well. Not sure it wasn't the emotional aspect for him as much as the bringing out the bad boy side, but see your point.
As far as me not being so nice and sweet? Hmmm... strength and power without malice. Hadn't thought of it that way before. I can't decide if you're trying to tell me I have more power than I think I do or if I'm not so nice and sweet! But I like the paradigm you used. Coincidentally, I just saw that movie a couple of weeks ago (read the book many moons ago) and remember that line. At any rate, it sounds like me. This is one of the things I like about this board and everyone on it, they help you take a good look at yourself.
BTW, I like your DB name. I am a huge LOTR fan. The wise King Theoden ... he prepared himself for the worst but did not lose courage!